The coefficients of the thermal conductivity (kappa) and first viscosity (eta) in thin helium films are evaluated explicitly as a function of temperature via phonon-phonon, phonon-roton, and roton-roton scattering. Above about 0.8 K, phonon-roton scattering and five-phonon processes are the main contributors to both coefficients. Below about 0.8 K, both coefficients increase exponentially with decreasing temperature. At temperatures below 0.3 K, kappa/sub ph/ has a T/sup -5/ dependence, while eta/sub ph/ shows exponential and T/sup -1/ dependencies. In the case of eta/sub ph/, the former is due to phonon-roton scattering and the latter originates from three-phonon processes. The coefficient kappa/submore » r/ from roton-roton scattering varies as T/sup -1/, and the roton part eta/sub r/ of the first viscosity is independent of temperature.« less

The bootstrap current [ital J][sub [ital b]]=[minus][ital IcP][prime][ital B]/[l angle][ital B][sup 2][r angle] and [chi][sub [ital i]]= [radical]2[ital N][nu][sub [ital iM]][sub [ital iT]][sub [ital i]]([ital Ic]/[ital e])[sup 2][l angle]1/[ital B][sup 2][r angle]/[vert bar][del][psi] [vert bar][sup 2] are valid for both the banana and the Pfirsch--Schlueter regimes for any finite value of the collision frequency at a radius where the local aspect ratio [ital A] approaches unity. Here, [ital I]=[ital RB][sub [ital t]] with [ital R] the major radius, [ital B][sub [ital t]] the toroidal magnetic field strength, and the prime denoting the derivative with respect to the poloidal flux [psi].more » Thus, the bootstrap current does not vanish, even in the collisional regime, when [ital A] approaches unity. The physical reason for this dramatic result is that the magnitudes of the electron and ion parallel viscosity approach infinity as [ital A] approaches unity. This also indicates that the conventional theory underestimates the magnitude of bootstrap current in an ultralow-aspect-ratio tokamak.« less